A team of international researchers has discovered that the Earth's magnetic field experienced an unusually long and unstable polar reversal around 40 million years ago, lasting at least 70,000 years. This duration significantly exceeds previous estimates, shedding new light on the complexities of geomagnetic reversals. The study, published in the journal 'Earth and Environmental Communications', is based on an 8-meter-long sediment core extracted from the North Atlantic off the coast of Newfoundland.

The sediment layers contained tiny magnetic crystals that recorded the Earth's magnetic field direction at the moment of their deposition, allowing scientists to reconstruct the behavior of the magnetic field during the Eocene epoch. This crucial data illustrates not only the duration of the magnetic reversal but also the dynamics involved, providing insights into past environmental conditions and the potential implications for future geomagnetic activity.

The Earth's magnetic field acts as a protective shield, safeguarding the planet from charged particles emanating from the sun and outer space. When this field weakens during polarity reversals, the Earth becomes more susceptible to cosmic and solar radiation. The findings indicate one of the observed reversals lasted about 18,000 years, while the other extended for at least 70,000 years, contrasting with common estimates that usually place the duration of such reversals around 10,000 years.